Highly sensitive and quantitative fluorescent strip immunosensor based on an independent control system for rapid detection of tetrodotoxin in shellfish

Tetrodotoxin (TTX) in shellfish poses a serious public health threat, and there is thus an urgent need to develop an accurate approach for detecting TTX. In this study, a new method of rapid detection using an immune strip sensor achieved on-site detection of TTX in shellfish. Time-resolved fluorescent microspheres were used fluorescent labels that were conjugated with anti-TTX antibody as a detection probe. Meanwhile, a streptavidin-biotin system was introduced as an independent control system to make the fluorescence intensity of the control line more stable. The developed immune strip sensor could achieve rapid detection of TTX within 20 min; the detection limit was as low as 0.05 ng/mL with the linear range of 0.5-40 ng/mL, and the acceptable recovery was 97-102%. The reliability of this method for real sample detection was verified by the comparison to the results ultra-performance liquid chromatography/tandem mass spectrometry. The proposed method provides effective approach for instant screening and detection of TTX in shellfish samples.